According to ESPN's Adam Schefter, the contract is a one-year deal with a series of options that could make it worth $24 million over four seasons. Schefter added that the contract is likely to be a two-year, $12 million pact.
Following a four-year stint with the Kansas City Chiefs to begin his career, Carr signed with the Cowboys prior to the 2012 season and went on to become one of the few constants on their defense.
He has been among the NFL's most consistent and reliable corners since entering the league with no missed games and 144 career starts to his credit.
The 30-year-old also has 15 career interceptions and is among the most sure-handed and willing tacklers at his position.
Carr registered 61 tackles, nine passes defended and one interception last season for a Dallas team that made significant strides on defense and earned the No. 1 playoff seed in the NFC.
On the heels of a campaign that saw him secure his first interception since 2013, Carr expressed a desire to return to the Cowboys under the right circumstances, according to Jon Machota of the Dallas Morning News: "I love defending the star. I love representing everything that comes with the Dallas Cowboys organization, so that's first and foremost. But also, you have to play the game. There's a business side to it as well, and I'm prepared to do both."
Although Carr's ball-hawking skills aren't elite, his experience and veteran savvy made him an attractive option on the open market.
Most teams could benefit from a defensive back of Carr's ilk with so many high-volume passing offenses in the league, and that group includes the Cowboys.
Dallas faced a difficult situation entering free agency, however, as starting corners Carr and Morris Claiborne were set to test the free-agency waters.
With the Cowboys left to make tough decisions, the Ravens swooped in and strengthened their secondary significantly by signing Carr.
While Carr isn't quite a Pro Bowl-level performer and isn't considered a playmaker at cornerback, his solid play will make life easier for those around him in his new surroundings.
Baltimore already has a strong No. 1 corner in Jimmy Smith, but signing Carr will allow it to transition Tavon Young to a nickel role.
That strengthens the Ravens' cornerback group significantly, and with safeties Eric Weddle and Tony Jefferson in the fold as well, Baltimore now boasts a supremely talented secondary.